Well, you can own and buy "pre-ban" AK 30 round mags in NY. But I am **guessing** since Mini-14's are not milsurplus like AK's or SKS-M/D's, they don't come under the same qualification. Mini-14's are considered modern sporting
firearms, and no modern
civilian firearm in NY can exceed 10 round capacity.
It is possible Mini-14 pre-ban mags may
be legal, but bozo's like Bloomberg, Cuomo, & Spitzer have sued out of state gun shops (with my tax dollars
) on spurious charges to discourage gun sales to NY. Even though the charges are bogus, the expense of defending themselves in court has made gun shops reluctant to deal with NY.
For example, I once tried to buy some pre-ban AK mags from Classic Arms, and they would not do it when they found out I lived in NY.But it's perfectly legal for me to own them, as long as they are milsurplus, and not of modern manufacture.
Check with some gun dealers, they should be able to tell you for sure.